Adding a circuit

[Winds of Change]

Has anyone actually accessed the back side of a fuse block to add a circuit? As in when you have a live spare wouldn't you have to wire it up from behind inorder to not look or be Jerry rigged? I know there are fuse taps and such. Just wondering is that what is actually supposed to done or not? Sometimes I am to anal for my own good.

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[Mark S.]

Has anyone actually accessed the back side of a fuse block to add a circuit? As in when you have a live spare wouldn't you have to wire it up from behind inorder to not look or be Jerry rigged?

I would just stick with a fuse tap. The more things you disassemble the greater the likelihood of improper reassembly or damage during reassembly. Fusetaps are the least intrusive way (no cutting or splicing of OEM wires) to get power to accessories. Besides, no one can see the fusebox anyway.

 

[Winds of Change]

I would just stick with a fuse tap. The more things you disassemble the greater the likelihood of improper reassembly or damage during reassembly. Fusetaps are the least intrusive way (no cutting or splicing of OEM wires) to get power to accessories. Besides, no one can see the fusebox anyway.

Agreed. I was just wondering it there was something I've been missing all these years with that spare fuse like a dangling wire somewhere to connect to.

 

[Major Kong]

the use of a fuse tap has it's merits
ease of installation
simplifies identification of wired in application
allows easy switch to other slot if needed

doesn't need to look jerry-rigged
clean appearance not that difficult to achieve

 

[LazyDirtFarmer]

I use fuse taps... no worries. Unless I'm wiring anything that has a high current draw like an audio amp, woofer, two-way radio, etc... In which case I try to go direct to the battery with a 14, 12 or 10 gauge wire with an in-line fuse, depending on the application. The fuse box is likely wired with 18 or 16 gauge.

 

[Rodrigo_V_U]

you can use this: https://www.aliexpress.com/item/4000648828410.html?spm=a2g0o.order_list.0.0.171f1802zAhBvP

BS uses MICRO 2

in the fuse box under the dash, number 3 is available.

 

[Winds of Change]

you can use this: https://www.aliexpress.com/item/4000648828410.html?spm=a2g0o.order_list.0.0.171f1802zAhBvP

BS uses MICRO 2

in the fuse box under the dash, number 3 is available.

Maybe I am not being clear. Yes sometimes I overthink and overcomplicate stuff. If fuse #3 is available does Ford expect us to use a fuse tap for the available fuse/circuit? I am familiar with fuse taps and have used them. I was just wondering if auto manufaturers prefer a specif method. I appologize for being obtuse. LoL. Mostly it was just something I wondered about.

 

[LazyDirtFarmer]

Maybe I am not being clear. Yes sometimes I overthink and overcomplicate stuff. If fuse #3 is available does Ford expect us to use a fuse tap for the available fuse/circuit? I am familiar with fuse taps and have used them. I was just wondering if auto manufaturers prefer a specif method. I appologize for being obtuse. LoL. Mostly it was just something I wondered about.

I think ford expects us to pay the Service Departments in their dealerships to install stuff... I'd be surprised if they have a widely distributed "OEM recommended" way to DIY anything, except maybe change a tire. I've had cars serviced by Ford with Fuse Taps before... The Techs either didn't notice or didn't care. They didn't even try to void my warranty

 

[Mark S.]

I was just wondering if auto manufaturers prefer a specif method.

You can find clues by looking at installation instructions for Ford accessories. For example, these instructions for installation of a light bar direct the use of provided wire splices.

I've done a lot of wiring (I built my own airplane, including the design and installation of its electrical system), and in my opinion a well designed and properly installed wire splice is the best option for a power tap. But that's based on some assumptions:

• You know the power demand for the new accessory.
• Power demand will not exceed circuit protection for the circuit you are tapping.
• Circuit protection for the existing circuit doesn't exceed limit for the wire you are installing
• You know how to properly install a splice.

Many people believe fuses are to protect the components they power, but that's not usually the case. Fuses protect the wiring. Most modern electronic components have their own circuit protection built in, or they are designed to withstand voltage/amperage spikes well beyond what they are likely to see in the environment in which they are installed.

What a fuse really does is prevent letting the smoke out of the wires. A short circuit can cause a wire to overheat, and in some cases catch fire and/or ignite other stuff near the wire. The fuse rating for a given circuit ensures the fuse will blow before enough current can go through a circuit to overheat the wiring that comprises the circuit. In fact, some circuit protection schemes involve the use of a fusible link, which is simply a shorth length of wire of smaller diameter than the primary wire (typically 4 AWG smaller) encased in a fire sleeve spliced into a circuit. If too much power goes through the circuit the smaller diameter wire will overheat and melt, and any ensuing fire will be contained within the fire sleeve.

This, incidentally, is why it's a really bad idea to replace a blown fuse with one that's rated higher than the original. As current increases the heat within a wire also increases. Hot wires do not flow electricity as well (higher resistance), so more current is required to power the given component. If the wire gets hot enough it can force resistance high enough to generate the necessary current to blow the fuse. The question is what caused the wire to get hot in the first place? If you simply replace a blown fuse with a higher rated one the wire must getter hotter still before the higher-rated fuse will blow. If the fuse rating exceeds the capacity of the circuit then you will let the smoke out of the wiring. Never replace a blown fuse with a higher rated one except in an emergency. Replace a blown fuse with an appropriately rated replacement, and if it also blows then you need to determine what is causing the circuit to overheat.

These (and other) factors are why I believe fuse taps are best for most people. A fuse tap does not require any specific knowledge of how electricity works, doesn't add to current draw on existing circuitry, does not require any special installation skills, and allows the use of a separate fuse appropriate to the circuitry for the accessory.

 

[LazyDirtFarmer]

You can find clues by looking at installation instructions for Ford accessories. For example, these instructions for installation of a light bar direct the use of provided wire splices.

I've done a lot of wiring (I built my own airplane, including the design and installation of its electrical system), and in my opinion a well designed and properly designed wire splice is the best option for a power tap. But that's based on some assumptions:

• You know the power demand for the new accessory.
• Power demand will not exceed circuit protection for the circuit you are tapping.
• You know how to properly install a splice.

Many people believe fuses are to protect the components they power, but that's not usually the case. Fuses protect the wiring. Most modern electronic components have their own circuit protection built in, or they are designed to withstand voltage/amperage spikes well beyond what they are likely to see in the environment in which they are installed.

What a fuse really does is prevent letting the smoke out of the wires. A short circuit can cause a wire to overheat, and in some cases catch fire and/or ignite other stuff near the wire. The fuse rating for a given circuit ensures the fuse will blow before enough current can go through a circuit to overheat the wiring that comprises the circuit. In fact, some circuit protection schemes involve the use of a fusible link, which is simply a shorth length of wire of smaller diameter than the primary wire (typically 4 AWG smaller) encased in a fire sleeve spliced into a circuit. If too much power goes through the circuit the smaller diameter wire will overheat and melt, and any ensuing fire will be contained within the fire sleeve.

This, incidentally, is what it's a really bad idea to replace a blown fuse with one that's rated higher than the original. As current increases the heat within a wire also increases. Hot wires do not flow electricity as well (higher resistance), so more current is required to power the given component. If the wire gets hot enough it can force resistance high enough to generate the necessary current to blow the fuse. The question is what caused the wire to get hot in the first place? If you simply replace a blown fuse with a higher rated one the wire must getter hotter still before the higher-rated fuse will blow. If the fuse rating exceeds the capacity of the circuit then you will let the smoke out of the wiring. Never replace a blown fuse with a higher rated one except in an emergency. Replace a blown fuse with an appropriately rated replacement, and if it also blows then you need to determine what is causing the circuit to overheat.

These (and other) factors are why I believe fuse taps are best for most people. A fuse tap does not require any specific knowledge of how electricity works, doesn't add to current draw on existing circuitry, does not require any special installation skills, and allows the use of a separate fuse appropriate to the circuitry for the accessory.

Thanks for posting that light bar install link... reading through it, It's not wired to the Fuse Box. It's spliced in using a barrel and heat shrink (WT-56814). I've used these types of splices before in marine grade applications; I'm going to use these if/when I have to splice something in on my BS from now on.

BTW: I used to be a IPC/WHMA-A-620 Certified IPC Trainer. Our company does work for the government.

 

[Mark S.]

I've used these types of splices before in marine grade applications; I'm going to use these if/when I have to splice something in on my BS from now on.

Just be aware that the people who wrote the instructions I linked to did all the necessary study to ensure they weren't overloading the circuit they tapped into, and that the fuse on the circuit is adequate for the added wiring. These are things you need to know if you splice into an existing power circuit.

For example, let's say you splice into a circuit using 14 AWG wire protected by a 15 amp fuse, but the wire for the accessory you are powering is only 18 AWG. A 15 amp fuse may not blow before 18 AWG wire smokes.

 

[LazyDirtFarmer]

Just be aware that the people who wrote the instructions I linked to did all the necessary study to ensure they weren't overloading the circuit they tapped into, and that the fuse on the circuit is adequate for the added wiring. These are things you need to know if you splice into an existing power circuit.

For example, let's say you splice into a circuit using 14 AWG wire protected by a 15 amp fuse, but the wire for the accessory you are powering is only 18 AWG. A 15 amp fuse may not blow before 18 AWG wire smokes.

It's Ohms Law

 

[Winds of Change]

So the 8Ga I used to wire up an Alternator might be a bit much for a dashcam

 

[LazyDirtFarmer]

I wired my GMRS today... I planned ahead so I only need to setup my fuse taps once. I Made a small wiring harness to tap into Fuse #3 and Fuse #24 with spade and SAE connectors. If I need to connect anything in the future, it'll be ez-pz

More details and installed pic is here: https://www.broncosportforum.com/forum/threads/transceiver-installation-thread-ham-cb-gmrs-radio-unit-and-antenna-installation-on-bronco-sport.1487/page-4#post-132044

 

[Winds of Change]

Is it a 50 watt radio? thus 2 fuse taps needed?

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